Hydrogen is flammable and can be explosive, with the following characteristics:
- Flammability range
Hydrogen is flammable in air concentrations between 4% and 75%. This is a much wider range than other common fuels, such as natural gas, which has a flammability range of 7% to 20%.
- Ignition energy
Hydrogen requires very little energy to ignite, especially under optimal combustion conditions. A small spark can ignite hydrogen.
- Flame
Hydrogen burns with a pale blue flame that's almost invisible during the day. Hydrogen fires also produce low radiant heat, so it can be difficult to sense the presence of a flame until you're very close to it.
- Explosiveness
Hydrogen can be explosive at concentrations between 18.3% and 59%. However, hydrogen is unlikely to explode in open air because it rises quickly.
- Safety
To prevent a fire or explosion, you should prevent hydrogen from mixing with an oxidizer. You can do this by ensuring proper system design, installation, and maintenance. If a leak occurs, you can dilute the hydrogen with ventilation to keep the concentration below its lower flammable limit.
Hydrogen is a colorless, odorless, tasteless, and non-toxic gas. It's used in oxyhydrogen welding and cutting, and to make other chemicals.